Search

The effects of bromate on the growth and physiological characteristics ofiChlorella vulgaris/iwere investigated via the static exposure experiments and tested by flow cytometry. The results showed that wheniChlorella vulgaris/iwas continuously exposed to bromate for 96 h at 8 mmol·Lsup-1/sup, the specific growth rates and cell membrane integrity decreased significantly, while the esterase activity, mitochondrial membrane potential and reactive oxygen species (ROS) increased significantly. The membrane-damaged cells could be found from the scanning electron microscopy analysis. It could be identified that ROS were overproduced in presence of bromate, which could not be eliminated byiChlorella vulgaris/iin time through self-regulation. The excess ROS could lead to abnormal situation of cell membrane integrity, esterase activity and mitochondrial membrane potential, disorder of physiology function and damage of cell structure. It could be concluded thatiChlorella vulgaris/idied or their growth was inhibited by the existence of bromate.

In the present study, the fate and long-term effect of TiO

Algogenic organic matters (AOM) generate from two parts, that are extracellular organic matters (EOM) and intracellular organic matters (IOM). This paper compared the structural characteristics of IOM and EOM originated from Microcystis aeruginosa using techniques including ultra violet-visible spectrum (UV-VIS), Fourier infrared spectrum (FT-IR) and three-dimensional excitation emission matrix (EEM) fluorescence spectroscopy. The results demonstrated that concentrations of the organic matter in EOM were less than that in IOM. EOM has less characteristic absorption peaks. There were more aromatic ring compounds, more protein and amino acids in IOM than EOM.

Algogenic organic matter (AOM), including extracellular organic matters (EOM) and intracellular organic matters (IOM) can interfere with drinking water treatment processes and cause water quality problems, among which the formation of disinfection byproducts (DBPs), microcystins and odor and taste compounds are of particular concern. In this study, the formations of THMs, Microcystins-LR and 2-MIB during four growth phase (lag phase, exponential phase, stationary phase and death phase) were investigated. The THMs formation potential of EOM and IOM were compared. Higher CHCl3 concentration was found in IOM than that in EOM. In the presence of bromide, more brominated-THMs generated, and the TTHMs increased more rapidly in EOM than IOM. The 2-MIB was found a similar trend with the MC-LR in the four growth phase. The total 2-MIB was gradually increased as a function of the time. The formation of MC-LR and 2-MIB depended on algae density.

In order to prove the rules of bromide ion remove in coagulation treatment stage in drinking water, by carrying out laboratory coagulation test in simulated water and the Songhua River raw water samples, the effects of bromine ion removal by coagulation of PAC, FeCl3 and the compound ferrous were investigated. The results showed that when the dosage of PAC was 60mg/L, the average removal rate of bromine ion was 50.6% by coagulation in the simulated water samples, and the rate was 44.8% in raw water samples of the Songhua River. In the conditions of FeCl3 dosage 70mg/L, the average removal rate of bromine ion was 56.1% in the simulated water sample, and the rate was 55.2% in raw water. When Reduce the same turbidity of drinking water, the effect of bromide ions removal by FeCl3 coagulation was better than that of PAC. When the dosage of compound ferrous (Ferrosilicon ratio of 1:1) as coagulant was 16.8mg/L, the bromide ions removal rate up to 67.6%.

In order to study the effect and influencing factors of bromate removal by ultraviolet treatment in drinking water, by carrying out laboratory test in simulated water and raw water samples, the action of UVC and UVA on bromate were investigated. The results indicated that bromate transformes into bromine ion under UVC treatment, but there was a small amount of UVA in the UVC lamp emission spectrum. Separate experiments on UVA treatment of bromate indicated that UVA could be considered as an interference factor for UVC treatment of bromate, and it should be restricted in the UVC lamp emission. The conversion of bromate to bromide was inhibited by suspended matter, which led to a rise of water turbidity and had influence on the reduction of bromate by UVC. When the water pH was 5.5~9 the same UV dose, the reduction of the bromate concentration by UVC treatment did not change significantly.

Carbon nanotubes (CNTs) have aroused widespread attention due to their high potential sorption capability for chemical pollutants. This review summarizes the adsorption mechanisms of organic chemicals and metallic ions with CNTs in aquatic environment and the factors affecting the adsorption. For a better understanding of the mechanism, future research works on combining the chemical experience and molecular dynamics (MD) is recommended.

This paper introduced an integrated control teaching system of building completely based on the technique of Lon bus. This system has the typed configuration of IBMS system-two classes network and three layers management (control), and overcomes the limitation of island of information and use protocol conversion gateway in building integration system, it’s a kind of building control integration system with truly open and with standard equivalent system network structure. The system has the characteristic of structure completed, technology.

Acute toxic effects of potassium bromate, sodium bromate and potassium bromide on luminescent bacteria, water flea, green alga and zebrafish were studied using standard toxic testing methods. The results showed that the pollutants had no effect on the luminous intensity of luminescent bacteria. The 96 h EC5. of potassium bromate on Scenedesmus obliquus was 738.18 mg x L(-1), 48 h EC50 on Daphnia magna and Moina was 154.01 mg x L(-1) was 161.80 mg x L(-1), while 48 h LC50 was 198 52 mg x L(-1), 175.68 mg x L(-1), and 96 h LC50 on zebrafish was 931.4 mg x L(-1). The 96 h EC50 of sodium bromate on Scenedesmus obliquus was 540.26 mg x L(-1), 48 h EC50 Daphnia magna and Moina was 127.90 mg x L(-1), 111.07 mg x L(-1), while 48 h LC50 was 161.80 mg x L(-1), 123.47 mg x L(-1), and 96 h LC50 on zebrafish was 1065.6 mg x L(-1). But the effects of potassium bromide on the above several kinds of aquatic organisms were far smaller than those of potassium bromate and sodium bromate. The toxic effects on test organisms were due to the impacts of bromate after the comparison of different pollutants, and the effects were more obvious with the increase of exposure time. The order of sensitivity to the toxic effects of bromate was Daphnia magna, MoinaScenedesmus obliquuszebrafishChlorella vulgaris, luminescent bacteria.

Silver carp were stocked in a pre-sedimentation pond in front of conventional water treatment processes in order to control Microcystis blooms in raw water. Silver carp effectively reduced the Microcystis flos-aquae concentrations, but green algae concentrations increased due to the ineffective filtration of silver carp for them. Water quality variations based on the effect of silver carp stocking on the two major phytoplankton communities (Microcystis and green algae) were evaluated by to investigate the relationship between water quality and phytoplankton cell concentrations in influent and effluent during Microcystis blooms period. Linear regression analysis indicated that the dominant species Microcystis governed the variation of turbidity and CODMn, and its concentration showed positive correlations with the two parameters. Meanwhile, the increase of green algae biomass led to the increase of pH and Chlorophyll a content, and showed obvious positive correlations with the two parameters in effluent.

The water solubility enhancement of 2,4´-DDT and 4,4´-DDT by humic acid and extracellular organic matter released from Microcystis aeruginosa was investigated by a ingenious sampling method and increasing apparent solute solubilities. Water solubility enhancements of the two DDT isomerizes by both humic acid and extracellular organic matter at the solution pH 7-11, and their solubilities increased with the increase of pH. Absorption coefficients Ciw (2,4´-DDT and 4,4´-DDT) increased with the increase of pH for HA and EOM, but Ciw for EOM are about two times than for HA at same TOC concentrations. The results suggested that more attentions should be paid to the enhancement of organic chemicals by EOM, especially in eutrophic water body where an increasing algae population usually appears, and the enhancement of DDT solubility by EOM may increase the risk of pesticide residues to organisms.

To reduce the production cost of polyhydroxyalkanoates (PHA) and disposal amount of excess sludge simultaneously, volatile fatty acids (VFAs) from alkaline excess sludge fermentation was used as carbon sources to synthesize PHA by unenriched mixed cultures. Released phosphorus and residual ammonium in the fermentative VFAs was controlled by adding magnesium to form struvite precipitation. Four VFAs liquids obtained was used to test the influence of initial carbon load and carbon to nitrogen ratio (C:N ratio) on the VFAs uptake rate, PHA storage rate and biomass growth rate. Results show that higher initial carbon substrate load results in relatively higher VFAs uptake rate and higher PHA storage rate, while higher initial C:N ratio results in relatively lower biomass growth rate from VFAs. VFAs generated from thermophilic alkaline sludge fermentation were a suitable carbon source for PHA production by mixed cultures.

Nano-sized titanium dioxide in aquatic environment poses potential impact on environment and human health. In this research, the impact of pH value, humic acid (HA) and divalent cations (Ca2+) on the stability of titanium dioxide nanoparticles(NPs) in the aqueous enviorment was investigated using a batch test. The results showed that the particle size of TiO2 NPs was not sensitive to the pH value but presented inversely proportional to zeta potential. The TiO2 NPs become more stable along with surface zeta potential, accompany with small particle size and high dispersion. In the presence of HA, the particle size was smaller and TiO2 NPs could be stabilized. This might be synergistic effect of the ligand exchange and electrostatic force. Meanwhile, NPs particle size increased with the addition of Ca2+ and the stability of TiO2 NPs became decreased.

Degradation of acid dye wastewater has been studued by using resin D072 load Fe2+ as heterogeneous Fenton catalyst. The effects of the initial PH of solution,the H2O2 adding doses,the amount of catalyst and the reaction temperature on the degradation of acid dye wastewater have been investigated in detail. According to experimental results, the optimal pH was pH3, the H2O2 adding doses was 333mg/L, the amount of catalyst and the reaction temperature were 10g/L and 27°C, respectively.

As an important oxidants, Chlorine dioxide was more useful in the decolorization of Reactive Red KE-3B, Reactive Blue KN-R, Reactive Red X-3B and Reactive Blue X-BR. It was found that the optimal pH=8，the optimal initial dosage of ClO2 and reaction time were 60 mg*L-1 and 15 min, respectively. The optimal reaction temperature of dyes were 80°C. Chlorine dioxide seems to be viable method for achieving significant decolorization of dying industry wastewater.

Chironomus kiiensis larvae which cannot be exterminated by conventional disinfection process propagates prolifically in eutrophic water body, and it therefore turns to be a potential problem encountered in drinking water quality. In this work, the quantitative experimental studies were carried out on removal of Chironomus kiiensis larvae in raw water by coagulation-sedimentation process. The coagulation jar test showed that the Chironomus kiiensis larvae could be partially removed from water by coagulation-sedimentation process. Based on it, removal effect of pre-oxidation combined with coagulation-sedimentation process on Chironomus kiiensis larvae was evaluated. The results showed that chlorine dioxide pre-oxidation possessed better removal performance than prechlorinion, and Chironomus kiiensis larvae in the raw water could be completely removed by chlorine dioxide pre-oxidation in combination with the coagulation-sedimentation process at chlorine dioxide dosage of 0.8mg/L. The pH in the range of 6-8 did not affect the inactivation efficiency of chlorine dioxide, whereas pH 10 resulted in around 10% decrease in removal rate. Meanwhile, the removal rate of Chironomus kiiensis larvae improved with the temperature increasing within the range investigated of 15-30°C. The removal rate was reduced by 6.7% when temperature reduced from 30°C to 15°C.

Resin D072 was more useful on the adsorption of Fe2+ as a heterogeneous catalyst in the presence of H2O2, which had high catalytic activity in the decolorization of reactive red KE-3B. The conditions of the adsorption of Fe2+ by D072 were optimized, including the initial pH, the Fe2+ concentration and reaction time. It was found that the optimal pH was pH3. The optimal initial concentration of Fe2+ and reaction time were 840 mg L-1 and 60 min, respectively. It illustrated that the adsorption behavior of Fe2+ by D072 obeyed Freundlich adsorption model. The decolorization reaction of reactive red KE-3B was still faster though the catalyst already used 10 times because Fe leaching from the catalyst was negligible. The heterogeneous catalyst seems to be viable method for achieving significant decolorization of dying industry wastewater.

In this paper, comparative experiments on the inactivation of Chironomid larvae by ozone and chlorine were conducted. In addition, batch experiments were performed in order to analyze the influence of pH value, organic precursor concentration and temperature on the inactivation efficiency of Chironomid larvae with ozone. Based on it, removal effect of different pre-oxidation combined with coagulation process on Chironomid larvae in raw water was evaluated. The results showed that ozone possessed better inactivation performance than chlorine, and complete inactivation of Chironomid larvae in raw water was obtained at ozone dose of 2.0 mg/L after 25 minutes of contact time. The inactivation rate of Chironomid larvae at pH 6.0 was higher than those found at pH 8.0 in same contact time. Meanwhile, the organic precursor had negative effects on inactivation, indicated by the decreasing inactivation rate from 100% at TOC concentration of 0 mg/L to 20.0% at 8 mg/L after 30 min of contact time. With regard to the temperature, the inactivation efficiency of Chironomid larvae improved with the temperature increasing within the range investigated of 10–25°C. The inactivation rate was reduced by 73.3% when temperature reduced from 25°C to10°C. The coagulation jar test showed that Chironomid larvae in the raw water could be completely removed by ozone pre-oxidation combined with the coagulation process at ozone dosage of 1.2 mg/L.

Zooplankton cyclops propagates profusely in waterbody, cannot be effectively inactivated by conventional disinfection process, and becomes a troublesome drinking water treatment problem. In this work, the qualitative and quantitative experimental studies were carried out on inactivation of zooplankton cyclops using oxidants, such as chlorine (Cl2), chlorine dioxide (ClO2), ozone (O3), hydrogen peroxide (H2O2), ozone/hydrogen peroxide (O3/H2O2), chloramines (Cl2-NH3) and potassium permanganate (KMnO4). The influences of various factors include different oxidant dosages, organic substance contents and pH values. The results showed that currently available oxidants used all might inactivate cyclops in some extent. According to the experimental results, chlorine dioxide, ozone, ozone/hydrogen peroxide and chloramines can be selected as effective oxidants for inactivating cyclops because of their strong inactivation abilities. Then the synergic removal effects on cyclops with ozone, ozone/hydrogen peroxide pre-oxidation followed by conventional water treatment processes were investigated. The results showed that ozone and ozone/hydrogen peroxide pre-oxidation can inactivate cyclops effectively, which then can be removed thoroughly by conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.65 mg/L of ozone and 6 mg/L of hydrogen peroxide, with the inactivation rate being 62% before conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.8 mg/L of ozone, with the inactivation rate being 50% before conventional water treatment processes. For different oxidants, when removal rate was the best, the inactivation rate was not the same. These results may provide reference and model for actual waterworks.

Starting with the occurrence of Cyclops in drinking water sources and its danger to drinking water safety, we extensively investigated the nature of its excess propagation by analyzing the effect of living space and predator pressure in the food chain on its survival. Then we developed an ecological project using fish biomanipulation, different to the conventional fishery culture technique, to control excess propagation of Cyclops. The control effects on Cyclops of four species of fish were investigated experimentally at a stocking density of 30g/m3 of water. Results showed that the food habit of the fish had a significant influence on the biological control of Cyclops. The propagation of Cyclops could be controlled effectively and also the water quality improved simultaneously by stocking filter-feeding fish, such as silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis). However, herbivorous Ctenopharyngodon idellus and omnivorous Cyprinus carpio had no obvious biological effects on controlling the growth of Cyclops and restoring water quality. The results further proved that under conditions of proper poly-culture densities of silver carp and bighead carp, the number of Cyclops might be controlled at very low levels and eutrophication might be abated by removing nutrients from the water body.

Nano-sized titanium dioxide in the aquatic environment has a potential impact on the environment and human health. In this study, the impact of pH value, dissolved organic matter (DOM) and divalent cations (Ca2+) on the stability of titanium dioxide nanoparticles (nano-TiO2) in an aqueous environment was investigated in batch tests. The results showed that the particle size of nano-TiO2 was not sensitive to pH value but was inversely proportional to zeta potential. The nano-TiO2 becomes more stable with surface zeta potential, accompanied by small particle size and high dispersion. In the presence of DOM, the particle size was smaller and the stability of nano-TiO2 could be enhanced. This might be a synergistic effect of the ligand exchange and electrostatic force. Particle size increased with the addition of Ca2+ and the stability decreased.

The synergic removal effect on Cyclops was studied with 4 kinds of dosages of pre-oxidants such as chloramines, chlorine, O3 and potassium permanganate composite followed by different sets of clarification treatment process pilot systems. The removal mechanisms of Cyclops in different treatment units were analyzed. The experiments results show that the inactivation rate of chlorine (25%) is the highest compared with the chloramines (21%), potassium permanganate composite (8%) and O3 (9%) in the pre-oxidation stage, while the removal rate is changed after the filtration and the sequence is chloramines (90%)chlorine (88%)O3 (83%)potassium permanganate composite (80%). Only chloramines can remove Cyclops by 100% of removal rate with the treatment process with the conventional active carbon unit. The 100% of removal effect doesn't depend on the highest inactivation rate,but the reasonable cooperation between the pre-oxidation and the clarification treatment process. The size of Cyclops and its life activity are the important influencing factors. The individual removal rate of filtration unit is the highest with no lower than 50%. The removal effect of air-flotation unit is influenced by the size of Cyclops and its life activity.

A coal‐based activated carbon was treated chemically with nitric acid, sodium hydroxide and ammonia for its surface modification, and its adsorption capacity was investigated with bromate. Several techniques were used to characterize the physicochemical properties of these materials including BET, XPS, pHpzc and Boehm titration. The results indicated that the specific surface area of the activated carbon decreased after oxidation with nitric acid. But the amount of surface acidic oxygen‐containing functional groups of the oxidized sample increased compared to the raw carbon and the points of zero charge (pHpzc) decreased. The specific surface area of the activated carbon also decreased after sodium hydroxide treatment and the points of zero charge increased. The changes of surface chemical properties after the ammonia treatment was opposite to the oxidized sample. As a result, the pHpzc of the carbon was increased to near pH9.3, the amount of surface basic groups was increased. Furthermore, the data of bromate adsorption on all the samples were fitted to the Langmuir isotherm model well which indicates monolayer adsorption. In addition, the adsorption capacity of ammonia treatment sample was the highest and its saturated adsorption capacity reached 1.55 mg/g. A strong correlation was found between basic groups and adsorption capacity of bromate. Enhancement of basic groups was favorable for bromate removal.

Cyclops of zooplankton threatens the drinking-water security because of the massive propagation in the polluted water resource and the ineffective treatment by conventional purification technology. The inactivation effects on Cyclops in the raw water of the pre-oxidants, such as chloramines, chlorine, potassium permanganate composite (PPC) and ozone, were discussed. And the synergic removal effects on Cyclops which pre-oxidation follows by purification process is investigated systemically with two pilot test equipments. The results show that, the removal effects on Cyclops depend on the reasonable coordination between pre-oxidation and the following water clarification process, the higher removal effects don't necessarily result from the higher inactivation effects. The most important treatment unit on removing Cyclops is the filter tank, and the removal effect of the individual filter unit can be about 50%. The removal effect of the air-floating unit may be about 20%, which is closely related to the size and the activity of Cyclops. Cooperating with pre-oxidation stage and air-floating, the removal effect of above 80% can be obtained after filtration, and about 90% of Cyclops can be removed after the advanced treatment. The 100% of removal effect on Cyclops can be obtained stably by clarification process after chloramines pre-oxidation.

To reduce the negative effect of algae on conventional water treatment, a full-scale research of removing algae from algae-laden raw water by stocking filter-feeding silver carp was processed. After the pretreatment in a presedimentation tank with silver carp, the concentration of phytoplankton, the biomass of cyanobacteria and Microsystis flos-aquae in algae-laden raw water with Microsystis flos-aquae its dominant species decreased 61.8%, 76.1% and 78.2% respectively. This effective decrease of algae load on conventional process created favorable conditions for water treatment. Analysis indicates that food habit of silver carp and algae size are two causes of different removal efficiency between cyanobacteria and green algae. The results show that biomanipulation of silver carp is applicable for treating algae-laden raw water in which colonial cyanobacteria is dominant.

Fly ash was investigated as a raw material for the preparation of a composite coagulant with sulfuric acid. Types of acid solution, H2SO4 concentration, ratio of H2SO4 to fly ash and stirring time were respectively examined as factors that influenced the efficiency of converting the iron and aluminum components into a composite coagulant and coagulation performance on domestic wastewater. The coagulant was attained at the condition of H2SO4-fly ash ratio of 5 mL/g, H2SO4 of 2 mol/L, stirring time of 4h and stabling time of 30 min, and contained Fe3+ of 0.010 8 mol/L with conversion efficiency of 11.4% and Al3+ of 0.035 4 mol/L with conversion efficiency of 4.3%. Removal efficiencies of COD and SS by this type of coagulant reached 70.4% and 91.9% respectively when treating domestic wastewater. This study provides a promising means to utilize fly ash for coagulation, which possibly makes wastewater treatment more economical and more sustainable.

The toxic effect of chlorine dioxide to the different instar larvae of chironomid was studied using raw water as test sample. Furthermore, the effect of temperature and contact time on toxicity of chlorine dioxide was observed. It was found that chlorine dioxide possessed significantly toxic effect, and the LC50 value of chlorine dioxide to the 4th instar larvae was 0.41 mg/L(24 h). The toxicity of chlorine dioxide declined with the development of instar larvae. The 1st instar larvae was most sensitive to chlorine dioxide among the four instars, and the LC50 value of chlorine dioxide to the 4th instar was 1.78 times of that of the 1st instar larvae. Temperature was proved to have significant positive effect on chlorine dioxide toxicity, and the toxicity at 30 degrees C was 2.16 times of that at 15 degrees C. The toxicity of chlorine dioxide was significantly improved with the contact time increasing from 12 h to 24 h, while it did not make much difference with the contact time increasing to 36 h.

Comparative experiments on the inactivation of cyclops by chlorine dioxide and chlorine were conducted. Batch experiments were performed in order to analyze the influence of pH value, organic precursor concentration on the rate of inactivation of cyclops with chlorine dioxide. In addition, the synergistic effect of different pre-oxidation followed by coagulation process on removal of cyclops in raw water was evaluated. It was found that chlorine dioxide possessed better inactivation effect than chlorine. Cyclops can be completely inactivated after 30 min of contact time by low dosage of chlorine dioxide (1.0 mg/L). The rate of inactivation was essentially the same at pH 5.7 and 8.0, and pH 9.8 resulted in the 10% of decrease in inactivation rate of cyclops than pH 5.7 - 8.0 in same contact time. The organic precursor concentration had negative effects on inactivation, and the higher the organic precursor concentration was, the lower inactivation rate of cyclops was achieved. The coagulation jar test showed that cyclops in the raw water could be completely removed by synergistic effect of chlorine dioxide pre-oxidation followed by coagulation process at chlorine dioxide dosage of 0.9 mg/L.

Cyclops of zooplankton propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfections process like chlorination due to its stronger resistance to oxidation. In this study, an ecological project was put forward for the excess propagation control of Cyclops by stocking the filter-feeding fishes such as silver carp and bighead carp under the condition of no extraneous nutrient feeding. The results of experiments with different stocking biomass showed that the propagation of Cyclops could be controlled effectively, and the water quality was improved simultaneously by impacting on nutriment level and plankton community structure at proper stocking density of 30 g/m3 of water. The growth of Cyclops may not be effectually controlled with lower biomass of fish (10 g), and the natural food chain relation may be destroyed for Cyclops dying out in water while the intense stocking of 120 g per cubic meter of water. In addition, the high predator pressure may accelerate supplemental rate of nutrients from bottom sediments to water body to add the content of total nitrogen and phosphorus in water.

For the purpose of solving the problem of low temperature and low turbidity water treatment, a pilot study was made on the treatment of Songhuajiang River raw water with low temperature and low turbidity by using membrane bioreactor (MBR) process, and the removal effects of organic pollutants and turbidity and membrane filtration period were also investigated. The results showed that the effluent turbidity was lower than 1 NTU and its removal efficiency was over 90%. The removal efficiency of permanganate index and UV254 were about 40% - 50% and 30% - 45%, respectively. The operation time of the MBR was as long as 60 - 70 hours. Adding powder activated carbon (PAC) has increased the organic pollutant removal efficiency but it has no significant influence on the membrane permeability. Therefore, the MBR was capable of effectively treating waters typically used for drinking water supplies, particularly when the low temperature and low turbidity water are treated. The effluent water quality of MBR was better than that of conventional process. PAC-MBR combined process can be used to enhance organic pollutants removal efficiency when raw water was polluted severely.

Mesocyclops leukarti of zooplankton propagates excessively in eutrophic water body and it cannot be effectively inactivated by the conventional drinking water treatment process. In order to tackle this problem, a study of removal effect on Mesocyclops leukarti with chlorine dioxide in a waterworks was performed. The results showed that Mesocyclops leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide preoxidation combined with the conventional drinking water treatment process. Higher oxidizability and molecular state of chlorine dioxide in water is the key to the inactivation of Mesocyclops leukarti. The chlorite, disinfection by-products (DBPs) of chlorine dioxide, was stable at 0.45 mg/L, which is lower than that critical value of the USEPA. GC-MS examination showed that the quantity of organic substance in the water treated by chlorine dioxide obviously decreased. Ames test further revealed that the mutagenicity was reduced by chlorine dioxide with respect to prechlorine. The propagation of Mesocyclops leukarti can be inactivated effectively and safely by chlorine dioxide pre-oxidation.

Cyclops of zooplankton propagates prolifically in eutrophic waterbody and it cannot be exterminated by conventional disinfection process. The mutagenicity of Mesocyclops leukarti and its extermination with oxidants in a drinking waterworks in China were studied. Among five oxidants for use in bench-scale, chlorine dioxide is the most effective and the potassium permanganate is the weakest against Mesocyclops leukarti under the same conditions. Full-scale results showed that Mesocyclops leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide preoxidation combined with conventional removal physical process. After filtration, chlorite, a by-product of prechlorine dioxide, is stable at 0.45 mg/L, which is lower than the critical value of the USEPA. GC-MS examination and Ames test further showed that the quantity of organic substance and the mutagenicity in water treated by chlorine dioxide preoxidation are obviously less than those of prechlorination.

The inactivation effects of ozone, hydrogen peroxide, O3/H2O2 processes on Cyclops of zooplankton were discussed. It was found that O3/H2O2 possessed more favorable inactivation effect on Cyclops compared with the others, in distilled water with 1.0 mg/L of O3 and 4 mg/L of H2O2 the inactivation effect was 100% after 30 min contacting; ozone also had favorable inactivation effect, the inactivation effect is 80% by 1.0 mg/L of ozone alone; while hydrogen peroxide didn't, there was almost no inactivation effect by 4 mg/L of H2O2. The best inactivation condition for O3/H2O2 processes, that was, two oxidants were added sequentially with interval in range of 30 to 60 seconds, for them ozone at first. And the influencing factors under various conditions such as the dose of hydrogen peroxide, organic substance content, pH value, etc. were researched and reported. It was found that the effect didn't changed largely with H2O2 on the range of 4 mg/L to 10 mg/L, and inactivation effects on Cyclops of O3/H2O2 were not sensitive to pH value, while it declined obviously as the organic content increased. Finally, synergic removal effect on Cyclops with O3/H2O2 preoxidation followed by clarification process was investigated. The results show that the removal effect on Cyclops is further strengthened by clarification processes after O3/H2O2 pre-oxidation.

The excessive propagation of Chironomid larvae (red worm) in the sedimentation tanks is a difficult problem for the normal function of waterworks. The toxic effect of liquid chlorine on the different instar larvae of Chironomid was studied using distilled water as test sample. Furthermore, the effect of pH value, organic matter content, ammonia nitrogen, and algae content on toxicity of liquid chlorine was observed. The results show that the tolerance of Chironomid larvae to liquid chlorine is strengthened with the increase in instar. The 24h semi-lethal concentration (LC50) of liquid chlorine to the 4th instar larvae of Chironomid is 3.39 mg/L. Low pH value and high algae content are helpful to improve the toxic effect of liquid chlorine to Chironomid larvae. In neutral water body, the increase in organic matter content results in the decrease in the death rate of Chironomid larvae. The toxicity of liquid chlorine differs greatly in different concentrations of ammonia nitrogen. The death rate of the 4th instar larvae of Chironomid in raw water is higher by contrast with that in sedimentation tanks water for 24h disposal with various amount of liquid chlorine.

The removal of disinfection by-products formation potential (DBPFP) in artificially intensified biological activated carbon (IBAC) process which is developed on the basis of traditional ozone granular activated carbon was evaluated. By IBAC removals of 31% and 68% for THMFP and HAAFP were obtained respectively. Under identical conditions, the removals of the same substances were 4% and 32% respectively only by the granular activated carbon (GAC) process. Compared with GAC, the high removal rates of the two formed potential substances were due to the increasing of bioactivity of the media and the synergistic capabilities of biological degradation cooperating with lactivated carbon adsorption of organic compounds. A clear linear correlation (R2 = 0.9562 and R2 = 0.9007) between DOC HAAFP removal rate and Empty Bed Contact Time (EBCT) of IBAC process was observed, while that between THMFP removal rate and EBCT of GAC was R2 = 0.9782. In addition certain linear correlations between THMFP, HAAFP and UV254 (R2 = 0.855 and R2 = 0.7702) were found for the treated water. For IBAC process there are also more advantages such as long backwashing cycle time, low backwashing intensity and prolonging activated carbon lifetime and so on.

Cyclops of zooplankton propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfections process like chlorination due to its stronger resistance to oxidation. In this paper, a full-scale study of chlorine dioxide preoxidation cooperating with routine clarification process for Cyclops removal was conducted in a waterworks. The experimental results were compared with that of the existing prechlorination process in several aspects: including the Cyclops removal efficiencies of water samples taken from the outlets of sedimentation tank and sand filter and the security of drinking water and so on. The results showed that chlorine dioxide might be more effective to inactivate Cyclops than chlorine and Cyclops could be thoroughly removed from water by pre-dosing chlorine dioxide process. The GC-MS examination and Ames test further showed that the sort and amount of organic substance in the treated water by chlorine dioxide preoxidation were evidently less than that of prechlorination and the mutagenicity of drinking water treated by pre-dosing chlorine dioxide was substantially reduced compared with prechlorination.

In order to remove the low turbidity present in surface water, a novel metal-polysilicate coagulant was used to treat the raw water taken from Tanjiang River in Guangdong Province. This study on the effects of Al/Fe molar ratio on the performance of a complex compound formed by polysilicic acid, aluminium and ferric salt (PAFS) showed that PAFS with Al/Fe ratio of 10:3 seemed to have the best coagulation performance in removing turbidity and color. Experimental results showed that under the conditions of polymerization time of 15 d, sedimentation time of 12 min, and pH of 6-8, PAFS with Al/Fe molar ratio of 10:3 had the best coagulation efficiency and lowest residual Al concentration. The turbidity decreased from 23.8 NTU to 3.23 NTU and the residual Al concentration was only 0.165 mg/L in the product water. It could be speculated that colloidal impurities and particulate Al were removed by adsorption bridging and electrical neutralization of long chain inorganic polymer coagulants.